Class 12 Biology · Chapter 13 · Test 1
Ecology and Biogeochemical Cycles
45 MCQs
45 questions · 40 min · 45 marks
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Sample questions
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Question 1
If you study the interaction between a herd of Markhors, the grass they eat, and the snow leopards that hunt them, which level of ecological organization are you focusing on?
- ASpecies
- BPopulation
- CCommunity
- DBiosphere
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Answer: C
A community consists of all the different populations of various species living and interacting in the same area.
Question 2
Nitrogen-fixers are present in the group/s:
- ABacteria and fungi
- BBacteria only
- CFungi only
- DBacteria, fungi and viruses
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Answer: B
The nitrogen-fixing organisms named in the text (cyanobacteria, Azotobacter, Clostridium and Rhizobium) are all bacteria.
Question 3
Which group of bacteria is involved in nitrification?
- AAzotobacter
- BNitrosomonas
- CClostridium
- DRhizobium
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Answer: B
Nitrosomonas and Nitrobacter are the soil bacteria that carry out nitrification.
Question 4
Which step of nitrogen cycle is accomplished by Pseudomonas?
- AAmmonification
- BNitrification
- CNitrogen fixation
- DDe-nitrification
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Answer: D
Denitrifying bacteria such as Pseudomonas and Thiobacillus convert nitrates back into nitrogen gas.
Question 5
How do nitrogen-fixing bacteria contribute to the nitrogen cycle?
- AReturn nitrogen (N2) to the atmosphere
- BChange ammonium to nitrate
- CChange N2 to ammonium
- DAbsorb nitrate from the soil
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Answer: C
Nitrogen fixers convert atmospheric N2 into ammonia or ammonium.
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